Add Users::SessionPolicy#destroy?

app/policies/users/session_policy.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class Users::SessionPolicy < ApplicationPolicy
+  def destroy?
+    !account&.user.nil?
+  end
+end

app/views/application/_navbar.html.erb

@@ -44,11 +44,13 @@
               <% if user_signed_in? %>
                 <div class="dropdown-divider"></div>
 
-                <%= link_to translate('users.shared.links.sign_out'),
-                            destroy_user_session_path,
-                            method: :delete,
-                            role: :button,
-                            class: 'dropdown-item' %>
+                <% if policy(%i[users session]).destroy? %>
+                  <%= link_to translate('users.shared.links.sign_out'),
+                              destroy_user_session_path,
+                              method: :delete,
+                              role: :button,
+                              class: 'dropdown-item' %>
+                <% end %>
               <% end %>
             </div>
           </li>

spec/policies/users/session_policy_spec.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe Users::SessionPolicy do
+  pending "add some examples to (or delete) #{__FILE__}"
+end